Strongly-coupled quantum critical point in an all-in-all-out antiferromagnet
Dimensionality and symmetry play deterministic roles in the laws of Nature. They are important tools to characterize and understand quantum phase transitions, especially in the limit of strong correlations between spin, orbit, charge, and structural degrees of freedom. Here, using newly-developed, high-pressure resonant X-ray magnetic and charge diffraction techniques, we have discovered a quantum critical point in Cd₂Os₂O₇ as the all-in-all-out antiferromagnetic order is continuously suppressed to zero temperature and, concomitantly, the cubic lattice structure continuously changes from space group Fd-3m to F-43m. Surrounded by three phases of different time reversal and spatial inversion symmetries, the quantum critical region anchors two phase lines of opposite curvature, with striking departures from a mean-field form at high pressure. As spin fluctuations, lattice breathing modes, and quasiparticle excitations interact in the quantum critical region, we argue that they present the necessary components for strongly-coupled quantum criticality in this three-dimensional compound.
Additional Information© 2018 The Author(s). Open Access. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/. Received: 4 May 2018. Accepted: 2 July 2018. Published 27 July 2018. We are grateful for stimulating discussions with J. Alicea, D. Belitz, L. Hozoi, J.C. Lang, P.A. Lee, G. Rafael, N. Shannon, O. Tchernyshyov, and M. Van Veenendaal. We thank J. Jureller for providing access to the optical Raman system and S. Tkachev at GSECARS for help on high-pressure Neon loading. The use of shared facilities of the University of Chicago Materials Research Science and Engineering Center (MRSEC) was supported by National Science Foundation Grant No. DMR-1420709. Use of the COMPRES-GSECARS gas loading system was supported by COMPRES under NSF Cooperative Agreement EAR−1606856 and by GSECARS through NSF grant EAR-1634415 and DOE grant DE-FG02-94ER14466. The work at Caltech was supported by National Science Foundation Grant No. DMR-1606858. The work at the Advanced Photon Source of Argonne National Laboratory was supported by the US Department of Energy Basic Energy Sciences under Contract No. NEAC02-06CH11357. D.M. acknowledges support from the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences, and Engineering Division. Author Contributions: Y.F. and T.F.R. conceived of the research. D.M. provided single crystal samples. Y.W., Y.F., A.P., Y.R. and J.-W. K. performed the measurements. Y.W., Y.F. and T.F.R. analyzed the data and prepared the manuscript. All authors commented on the manuscript. Data availability: The data that support the findings of this study are available from the corresponding authors upon request. The authors declare no competing interests.
ErrataThe original PDF version of the Article contained an error in the last sentence of the author affiliation information, which incorrectly read 'Correspondence and requests for materials should be addressed to T.$.R. (e-mail: firstname.lastname@example.org) or to Y.F. (e-mail: email@example.com)'. The correct version states 'T.F.R.' in place of "T.$.R.'. This has been corrected in the PDF version of the Article. The HTML version was correct from the time of publication.
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